Gaining some serious muscle (as in Hulk-like proportions) will definitely stretch your skin, but it usually won't stretch a tattoo enough to warp its appearance. Even if you lift heavy and often, the bulking up typically won't happen fast enough to impact the appearance of a tattoo.

If there is weight gain, there's a chance your tattoo will stretch out along with your skin. This can cause colors and lines to fade. In this case a 'touch-up' can be a solution. This also depends on the size and location of your tattoo.

The rate and speed of muscle growth will determine how much it will stretch the tattoo. If muscles are to grow steady and slow, it might not make the tattoo stretch that much, but if the muscle growth is rapid and sudden, it is more likely to make a noticeable difference in the tattoo.

When tattoos are placed over a muscle, the tattoo may stretch if you subsequently increase the muscle mass in that area. Moderate muscle growth should not have any noticeable effect upon a tattoo. However, sudden or significant muscle growth may damage the design and ink of the tattoo.